1. Field of The Invention
The present invention relates to a display apparatus and an adjusting method thereof, and more particularly, to a display apparatus including a color cathode ray tube comprising at least cathodes for the three primary colors and first and second grids wherein cutoff voltages of the respective cathodes for the three primary colors, and a voltage of the second grid may be desirably adjusted.
2. Description of The Related Art
In a color cathode ray tube used in a computer monitor for example, an adjusting mechanism is typically implemented for the optimization of fine image rendering, such as the rendering of line images etc., and not much emphasis is laid on the luminance since computers are generally used for data or word processing. Accordingly, the luminance level, although it depends on the size of a display, is kept at a low level, for example, a level around 100 to 150 nits. However, with the recent growth in the use of so-called multimedia applications on computer systems, there is an increasing demand for computer monitors to display dynamic picture images. However, it has been pointed out that picture images of such limited luminance would not promote powerfulness and sense of realism since the screen would be too dark.
Accordingly, in a case of a computer monitor utilizing a conventional cathode ray tube having predetermined cathode cutoff voltages and grid voltage, enhancement in the luminance would be attempted by increasing the level of, for example, input signals. However, this approach has a drawback, as it would significantly degrade the luminance life of the cathode ray tube. As a result, in a conventional apparatus, the adjustment is only made within a range below a given maximum luminance level, and any attempt to adjust the luminance to a level exceeding the predetermined level would typically result in collapsed peaks in a signal due to saturation occurred within a portion of its video signal circuitry, or in a case where the apparatus implements a protection mechanism for preventing the luminance level from exceeding a predetermined value, such an attempt would fail.
The present invention, invented in consideration with the above issues, attempts to solve those problems pointed out for the conventional computer monitor designed to provide a low level of luminance, that is, the screen too dark for providing powerful and realistic representation of dynamic picture images, and the luminance level limited to a certain value through implementation of a protection mechanism etc. for preventing an excessive increase in the luminance resulted from, for example, an increased input signal level, since such an increased input signal level would significantly degrade the luminance life of the cathode ray tube.
According to the present invention, a color cathode ray tube is provided, said color cathode ray tube comprising at least cathodes for the three primary colors and first and second grids, and being configured in a manner that cutoff voltages for the respective cathodes for the three primary colors and a voltage for the second grid are calculated using a common variable, and these voltages may be arbitrarily set, so that adequate luminance level control may be implemented by arbitrarily setting the cutoff voltages for the respective cathodes for the three primary colors and the voltage for the second grid, and at the same time, these voltages that are mutually associated may be configured in a simple manner.